Solanum nigrum L. weed plants as a remediation tool for metalaxyl-polluted effluents and soils

In this work, the phytoremediation potential of metalaxyl, a commonly used persistent, mobile and leachy fungicide, by Solanum nigrum L. plants was studied. The study revealed that this plant species can be used as an excellent metalaxyl phytoremediation tool, thus providing a cost effective and environmentally friendly clean technology for the decontamination of sites and effluents. As it can be sowed directly in the remediation site, is able to complete its life cycle without suffering major stress. Because it accumulates high amounts of the fungicide in the aboveground tissues, enables its concentration and proper disposal by cutting off the corresponding plant part. The study also suggests that the tolerance to metalaxyl is due to a suitable antioxidant response comprising proline accumulation and guaiacol peroxidase and glutathione-S-transferase enhanced activities, that reduce oxidative damage to the plant organs.     

Diversity of shrub tree layer, leaf litter decomposition and N release in a Brazilian Cerrado under N, P and N plus P additions

This study investigated changes in diversity of shrub-tree layer, leaf decomposition rates, nutrient release and soil NO fluxes of a Brazilian savanna (cerrado sensu stricto) under N, P and N plus P additions. Simultaneous addition of N and P affected density, dominance, richness and diversity patterns more significantly than addition of N or P separately. Leaf litter decomposition rates increased in P and NP plots but did not differ in N plots in comparison to control plots. N addition increased N mass loss, while the combined addition of N and P resulted in an immobilization of N in leaf litter. Soil NO emissions were also higher when N was applied without P. The results indicate that if the availability of P is not increased proportionally to the availability of N, the losses of N are intensified.     

Count, identification and antimicrobial susceptibility of bacteria recovered from dental solid waste in Brazil

In Brazil, few studies on microbial content of dental solid waste and its antibiotic susceptibility are available. An effort has been made through this study to evaluate the hazardous status of dental solid waste, keeping in mind its possible role in cross-infection chain. Six samples of solid waste were collected at different times and seasons from three dental health services. The microbial content was evaluated in different culture media and atmospheric conditions, and the isolates were submitted to antibiotic susceptibility testing. A total of 766 bacterial strains were isolated and identified during the study period. Gram-positive cocci were the most frequent morphotype isolated (48.0%), followed by Gram-negative rods (46.2%), Gram-positive rods (5.0%), Gram-negative-cocci (0.4%), and Gram-positive coccobacillus (0.1%). Only two anaerobic bacteria were isolated (0.3%). The most frequently isolated species was Staphylococcus epidermidis (29.9%), followed by Stenotrophomonas maltophilia (8.2%), and Enterococcus faecalis (6.7%). High resistance rate to ampicillin was observed among Gram-negative rods (59.4%) and Gram-positive cocci (44.4%). For Gram-negative rods, high resistance was also noted to aztreonam (47.7%), cefotaxime (47.4%), ceftriaxone and cefazolin (43.7%), and ticarcillin-clavulanic acid (38.2%). Against Gram-positive cocci penicillin exhibit a higher resistance rate (45.0%), followed by ampicillin, erythromycin (27.2%), and tetracycline (22.0%). The present study demonstrated that several pathogenic bacteria are present in dental solid waste and can survive after 48 h from the waste generation time and harbor resistance profiles against several clinical recommended antibiotics.     

Biodegradable Films Based on Blends of Gelatin and Poly (Vinyl Alcohol): Effect of PVA Type or Concentration on Some Physical Properties of Films

The aim of this work was to develop biodegradable films based on blends of gelatin and poly (vinyl alcohol) (PVA), without a plasticizer. Firstly, the effect of five types of PVA with different degree of hydrolysis (DH) on the physical properties of films elaborated with blends containing 23.1% PVA was studied. One PVA type was then chosen for the study of the effect of the PVA concentration on the mechanical properties, color, opacity, gloss, and water solubility of the films. The five types of PVA studied allowed for films with different characteristics, but with no direct relationship with the DH of the PVA. Therefore, the PVA Celvol^®418 with a DH = 91.8% was chosen for the second part, because they produced films with greater tensile strength. The PVA concentration affected all studied properties of films. These results could be explained by the results of the DSC and FTIR analyses, which showed that some interactions between the gelatin and the PVA occurred depending on the PVA concentration, affecting the crystallinity of the films.     

Development,validation and matrix effect of a QuEChERS method for the analysis of organochlorine pesticides in fish tissue

This study aims to develop and validate a method to determine OCPs in fish tissues, minimizing the consumption of sample and reagents, by using a modified QuEChERS along with ultrasound, d-SPE and gas chromatography with an electron capture detector (GC-ECD), refraining the pooling. Different factorial designs were employed to optimize the sample preparation phase. The validation method presented a recovery of around 77.3% and 110.8%, with RSD lower than 13% and the detection limits were between 0.24 and 2.88 μgkg^?1, revealing good sensitiveness and accuracy. The method was satisfactorily applied to the analysis of tissues from different species of fish and OCPs residues were detected. The proposed method was shown effective to determine OCPs low concentrations in fish tissues, using small sample mass (0.5 g), making the sample analyses viable without the need for grouping (pool).     

Adsorption Kinetics of Dyes in Single and Binary Systems Using Cyanoguanidine-Crosslinked Chitosan of Different Deacetylation Degrees

The crosslinking of chitosan with cyanoguanidine shows some advantages, such as the improved the stability in acid solutions and the decrease of adsorbent cost. In this work, cyanoguanidine-crosslinked chitosan and pure chitosan were prepared to apply in the adsorption of Food Yellow 4 (FY4) and Food Blue 2 (FB2), in single and binary systems. Effects of pH and deacetylation degree (DD) of chitosan in adsorption were evaluated. The adsorbents were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The kinetic data were analyzed by pseudo-first order, pseudo-second order and Avrami models. The conditions of pH 3 and DD 95% were the more suitable to reach the highest adsorption capacities in all experimental assays. Under these conditions, the adsorption capacities for FY4 were approximately of 392 and 200 mg g^?1 and, for FB2 were approximately of 370 and 184 mg g^?1, respectively, in the single and binary systems. The Avrami model was suitable to represent the kinetic curves in all conditions, and the highest adsorption capacities were found for FY4 in binary aqueous system, being for the pure chitosan of 229 mg g^?1 and crosslinked chitosan of 218 mg g^?1. The Langmuir and extended Langmuir models presented a good fit to the equilibrium data in both systems. It was found that, the chitosan crosslinked with cyanoguanidine improved the chemical stability of chitosan as adsorbent.     

Economic water management decisions: trade-offs between conflicting objectives in the sub-middle region of the São Francisco watershed

Hydro-economic models can measure the economic effects of different reservoir operating rules, environmental restrictions, maintenance of ecosystems, technical constraints, institutional constraints, land use change, and climate change. To determine the optimal economic water allocation, for its main uses in the sub-middle of the São Francisco River Basin, a hydro-economic optimization model was developed and applied. Demand curves were used rather than fixed requirements for water resources. The results show that operation rules of reservoirs and institutional constraints, such as priorities for human consumption, have high impacts on costs and benefits of the principal economic uses in the study area. Especially, costs of environmental demands, like minimum ecological river flow, have high impacts on the water resource management. Scarcity costs of irrigation users associated with maintaining ecosystems and environmental constraints are particularly significant. The results from this study provide a better understanding of the water trade-offs for future policymaking and efficient water management. Policymaking for the water resources should consider the food-water-energy-environment nexus at a regional scale to minimize environmental and economic cost under water scarcity and land use change.     

Carbon-optimised land management strategies for southern Amazonia

Regional Environmental Change -     

Paradigm changes in freshwater aquaculture practices in China: Moving towards achieving environmental integrity and sustainability

Contribution of fisheries and aquaculture to global food security is linked to increased fish consumption. Projections indicate that an additional 30–40 million tonnes of fish will be required by 2030. China leads global aquaculture production accounting for 60% in volume and 45% in value. Many changes in the Chinese aquaculture sector are occurring to strive towards attaining environmental integrity and prudent use of resources. We focus on changes introduced in freshwater aquaculture developments in China, the main source of food fish supplies. We bring forth evidence in support of the contention that Chinese freshwater aquaculture sector has introduced major paradigm changes such as prohibition of fertilisation in large water bodies, introduction of stringent standards on nutrients in effluent and encouragement of practices that strip nutrients among others, which will facilitate long-term sustainability of the sector.     

The invisibility of fisheries in the process of hydropower development across the Amazon

We analyze the invisibility of fisheries and inadequacy of fishers’ participation in the process of hydropower development in the Amazon, focusing on gaps between legally mandated and actual outcomes. Using Ostrom’s institutional design principles for assessing common-pool resource management, we selected five case studies from Brazilian Amazonian watersheds to conduct an exploratory comparative case-study analysis. We identify similar problems across basins, including deficiencies in the dam licensing process; critical data gaps; inadequate stakeholder participation; violation of human rights; neglect of fishers’ knowledge; lack of organization and representation by fishers’ groups; and lack of governmental structure and capacity to manage dam construction activities or support fishers after dam construction. Fishers have generally been marginalized or excluded from decision-making regarding planning, construction, mitigation, compensation, and monitoring of the social–ecological impacts of hydroelectric dams. Addressing these deficiencies will require concerted investments and efforts by dam developers, government agencies and civil society, and the promotion of inter-sectorial dialogue and cross-scale participatory planning and decision-making that includes fishers and their associations.